Fuse block



July 3,v 1934. H Jl L FRANK '1,965,410

FUSE BLOCK Filed July 14, 1935 llllllllnllllllnml INVENTOR.

BY MJ/@ ATTORNEY.

Patented July 3, 1934 UNITED STATES FUSE BLOCK Harrison J. L. Frank, Detroit, Mich., assignor to Bulldog Electric Products Company, Detroit,

Mich., a corporation of West Virginia Application July 14, 1933, Serial No. 680,374

4 Claims.

The inventions of this application relate to fuse blocks and parts thereof, and the principal object of the inventions of this application is the provision of a fuse block, substantially as shown in application No. 49,709, filed August 12, 1925, which resulted in Patent No. 1,833,158, November 24, 1931, and application No. 374,878, filed June 29, 1929.

An object of the inventions of the instant application is to provide a fuse block, whose base is moulded of porcelain or the like, in one piece, and having, on its under surface, channels for conducting straps or bus bars, and, on its upper surface, upwardly opening depressions for the reception of electrical sockets including plug-.fuse shells and their associated electrical parts. Fuse blocks generally like that which is here disclosed and which will be here described are not broadly novel. However, the bases-of such fuse blocks have generally included a bottom portion and a top portion, moulded separately from insulation material and then joined by screws or the like to form a suitable fuse block base. The disadvantages of a multi-piece construction are readily apparent. Considerations of expense and inconvenience of manufacture, of difficulties of assembly, and of electrical safety, militate against the use of multi-piece bases for fuse blocks and render it desirable to use one-piece bases for fuse blocks,

such as those of the invention.

A further object of the inventions of the instant application is the provision of novel specific details of fuse blocks and parts thereof.

Other objects and advantages of the inventions of this application will presently appear to those skilled in the art upon reference to the following description of the embodiment thereof that is shown in the appended drawing.

In this drawing,

4o Fig. 1 is a top plan view of a fuse block of the invention, only one of the (four) depressions thereof being shown as equipped with plug-fusereceiving electrical sockets, only one of the (two) conducting straps or bus bars thereof being shown in place, and only a portion of the neutral strap and its associated binding posts being shown.

Fig. 2 is a bottom plan view of the base per se, one bus bar of the block being shown in place, and other electrical parts being omitted for purposes of clarity. Y

Fig. 3 is a side elevation of the porcelain base yoi.' the fuse block, electrical parts being omitted for the purpose of illustrating the moulded insulation base more clearly.

Fig. 4 is a right end view of the block, two bus bars and their associated parts being shown in end elevation.

Fig. 5 is a transverse section view, as if on line 5 5 of Fig. 1, part of 'the bottom of the mounting box, in which the fuse block is disposed, being shown, and part of the front or masking plate of the mounting box also being shown, to illustrate the association of the fuse block with the mounting box commonly used.

Fig. 6 is a partially cut away left end View, as if on line 6 6 of Fig. 1, showing the neutral strap and its associated parts.

Fig. 7 is an elevational section through an alined pair of plug-fuse-receiving sockets, as if on line 7 7 of Fig. 1.

Fig. 8 is a fragmentary sectional view through a plug-fuse-receiving socket, as if on line 8 8 of Fig. 1.

Fig. 9 is a fragmentary sectional view illustrating the manner in which a portion of the block is moulded, and is intended to illustrate a characteristic which permits the block to be made in one piece.

For an understanding of the drawing, reference numerals are applied to parts therein shown, and these are referred to in the following detailed description, like numerals referring to like parts.

The fuse block includes a one piece base molded of insulating material, such as porcelain or the like, and associated electrical parts.

The base itself includes a centralrngass 10 having at its lower portion end projections 12 14, the former providing a seat for the neutral strap 16 and the latter providing seats for the ends of bus bars 18, disposed under the central mass 10 and projecting through openings 20. The seat 14 is so formed that the top surface thereof, at the openings 20, is below the level of the bottom surface of the mass 10 at the same openings, and this is one feature that permits the base to be made in one piece.

As an illustration of the value of so proportioning and shaping the parts, reference is had to Fig. 9 which shows a portion of the central mass 10 and a portion of the seat 14 as they are molded integrally between an upwardly and vertically moving bottom die A and a downwardly and vertically moving top die B". It is observed that a right hand surface a of the bottom die wipes past a left hand surface b of the top die to create the opening 20 which opens the space under the bottom surface of'the mass 10 to the space above the top surface of the seat 14, this opening permitting a bus bar 18 to be passed therethrough, and be disposed under the mass 10,

but with an end thereof above seat 14 to be accessible from the top of the block.

Symmetrically disposed in the central mass 10 are a plurality (four shown) of depressions 26 opening upwardly, and these receive threaded socket shells 28 into which are to be threaded plug fuses. These depressions 26 are provided with vertical holes 30 alined with large holes in the bottoms of the shells 28, and through these holes pass screws 31 which tap into the bus bars 18 that underlie the depressions, these screws holding the bus bars 18 in assembly with respect to the base, and also serving as center contacts for the electrical sockets of the base, for engagement with the center or tip contacts of the plug fuses to be threaded into the socket shells 28, the screws 3l having hexagonal heads, as shown, to provide such center contacts. The depressions 26 are further provided with a plurality of small vertical depressions 32-33 which do not pass through the bottom of the mass 10 but project downwardly only part of the way to provide true depressions rather than openings.

The depressions 26 are further provided with test slots 34 in their side walls, the slots tapering, as shown in Fig. 5, so that they are open to the top of the base and to the insides of the depressions, and thus to the shells 28, but they do not pass through the bottom of the base. These slots and their function are more particularly described in Patent No. 1,833,158.

The central mass is also provided with (two) vertical holes 36 which pass through to the bottom thereof, and which open to channels 38 on the under surface of the mass 10, in which channels are disposed the bus bars 18. These holes permit test leads to be inserted through the block to engage the bus bars 18.

The channels 38 are formed by a longitudinal central barrier 40 between them, which barrier isolates the bus bars 18 from each other, and by side wall vertical ledges 42, projecting downwardly from the central mass 10, these ledges shielding the bus bars from outside the block.

The ledges are centrally bored at 44 and counterbored as at 46, 47, for the reception of mounting bolts 48 which pass through the bores 44 and have their manipulable heads 49 disposed in the counterbores 46, to be accessible from the top of the block, the bolts passing through and tapping into tapped holes 50 of the sheet metal wall 52 forming the bottom of the mounting box in which the fuse block is disposed, the counterbores at 47 providing clearance for the extruded edges of the tapped holes 50.

The top surface of the central mass 10 is cut down at its edges to provide seats 54 for the adjacent edges of a large hole in a front or masking plate 56 which surrounds the block and forms a front for the mounting box in which the block is disposed. The central mass projects a very slight distance above the surface of the masking plate, the base being otherwise concealed by the masking plate.

The side walls of the central mass, near its rounded corners 57, are provided with side openings 58 through which may be passed (four) conductors whose ends are to be connected to the bottoms of the socket shells 28 by binding screws 60, these screws passing through the bottoms of the socket shells 28 and disposing themselves in the aforementioned depressions 32, it being observed that the upper edges of these depressions are chamfered to provide clearance for the chamfered edges of the tapped holes in the bottoms of the socket shells`through which pass and into which are tapped the binding screws 60, these chamfered edges providing depressions in the socket shell bottom, under the heads of screws 60, into which the bared ends of conductors connected to the shells are bent by the screws 60. The side openings 58 open to the bottom of the mass 10 through openings 61, which are formed by upwardly projecting parts of the bottom die A, these openings 61 permitting the side openings 58 to be formed in a base that is molded in one piece, and by means of simple dies thatmove vertically only, and without requiring multislide dies.

The seat 12 is provided with a pair of raised end barriers 62 curved to conform to the curved ends of the neutral strap 16, and these barriers project endwise from the central mass l0 so as to form integral continuations of the same. The barriers are countercut at 63, to provide seats for insulation covers that overlie the neutral strap and the associated binding screws. The bottom surface of the central part of the seat 12 is continued downwardly, as at 64, to merge with the central barrier 40, the portions 64 engaging the bottom wall 52 of the mounting box and form ing a support for the fuse block, another support for the block being the bottom surface of the seat 14.

The support 64 is vertically bored as at 66 and counterbored as at 68 for the reception of a screw 70 whose head is disposed in the counterbore 68 neutral strap 16 from the top of the block, pro- 1 viding binding posts for the (four) circuit con-` ductors.

Itis observed that the (four) circuit conductors connected to the (four) binding posts 76 form one side ofeach of the (four) circuits fed by the block and that the other side of each of the same (four) circuits is formed by one of the (four) conductors of opposite polarity passed into the socket shells through the side openings 58. It, therefore, will be seen that the barriers 62 shield and isolate the conductors that pass into the block through the openings 58 from the opposite polarity conductors that are connected to the binding posts 76, and consequently enhance the electrical perfection of the'fuse block.

The center and end of seat 14 are provided with upwardly projecting portions 80-81 which merge with the central mass 10. The central portion 80 forms a barrier between the ends of the bus bars 18 which project through the openings 20 and is provided with a central bore 82 which receives a screw (ndt shown) whose head rests in a countersink 83 and whose shank projects upwardly past the top of the block to thread into a tapped hole of the cover 56, this screw serving 7- block, for a 11G-220 volt system, the two outside ones, representing a difference of 220 volts, are connected to the bus bars by the binding posts 84, and the third or neutral conductor is connected to the block by the neutral strap binding post 'Z0- 72. The (eight) conductors representing the (four) circuits which are accommodated by the block shown are connected to the block in (four) pairs, one side of each circuit being connected to the (four) binding posts 76 and the other side of each of the same circuits being connected to the binding screws 60 in the socket shells.

Each socket shell 28 is shown as including a conventional threaded shell to whose bottom is integrally secured, by the binding screw 60 which threads into a tapped hole thereof, a bottom plate 90. This plate in effect forms part of the shell bottom and is formed with a lug (not shown) which seats itself in the previously described depression 33 in the bottom of the depression 26 to align the entire socket shell properly with respect to the depression in the central mass 10.

The bottom of each socket shell 28 and the bottom plate 90 are provided with aligned large openings, not shown, and the edge of the opening in the bottom plate is bent upwardly to provide a lug 92 which aligns the socket shell to the plate. Between this lug and the side wall of the socket shell, and resting on the bottom thereof, is an insulating washer 94. Through this washer and through the large openings in the composite bottom of the socket shell passes the hexagonally headed center contact screw 31 which taps into the bus bar 18, the contact screw being insulated from the socket shell 28 by the washer 94 and by the clearance between the shank of the screw and the edges of the hole in the composite bottom of the socket shell. The lug 92 cooperates with the edge of the washer 94 to maintain the washer in its proper relative position.

The composite bottom of each socket shell, around the tapped hole through which the binding screw 60 passes, is downwardly deformed so that a circuit conductor, passed through the hole 58 in the side wall of the central mass 10 and through an aligned hole 96 in the side wall of the socket shell 28, is downwardly deformed as the screw 60 is threaded down, the deformation of the conductor end interlocking the latter after it is inserted undeformed and as it is connected and bound to the bottom of the socket shell.

Now having described in detail the fuse block and its parts, reference will be had to the following claims which determine the scope of the invention, it being understood that except as limited, by these claims, the invention is not to be considered as limited to the specific form of fuse block shown.

f I claim:

1. A fuse and connection block construction of the character described including a one piece base of molded insulation material, having a central mass provided with a depression opening to its top surface and containing a socket shell, a ledge in the nature of an end projection near the lower part of an end of the central mass, the inner part of the top surface of the ledge being below the adjacent part of the bottom surface of the central mass, these surface parts meeting to form an end opening communicating the space below the central mass with the space above the ledge, through which opening may pass a bus bar underlying the central mass and having an end overlying the ledge, the bus bar being assembled with the base by being passed through said opening and having its end accessible from the space above the block and the ledge, the central mass having a side opening communicating the space to one side of the block with the interior of the depression, through which side opening a conductor terminal may be introduced into the interior of the depression, a shelf in the nature of an end projection near the lower part of a second end of the central mass, and having a conducting strap thereon provided with binding screw means, a. binding screw in the socket shell in line with the side opening for clamping a conductor inserted through said side opening into electrical connection with the shell, and a second binding screw in said socket shell having a head insulated from said shell and forming a center contact therefor, and having a shank threaded into the aforementioned bus bar.

2. A fuse and connection block construction of the character described including a one piece base of molded insulation material, having a central mass provided with a depression opening to its top surface and containing a socket shell, a ledge in the nature of an end projection near the lower part of an end of the central mass, the inner part of the top surface of the ledge being below the adjacent part of the bottom surface of the central mass, these surface parts meeting to form an end opening communicating the space below the central mass with the space above the ledge, through which opening may pass a bus bar underlying the central mass and having an end overlying the ledge, the bus bar being assembled with the base by being passed through said opening and having its end accessible from the space above the block and the ledge, the central mass having a side opening communicating the space to one side of the block with the interior of the depression, through which side opening a conductor terminal may be introduced into the interior of the-depression, a shelf in the nature of an end projection near the lower part of a second end of the central mass, and having a conducting strap thereon provided with binding screw means, and means in the socket shell in line with the side opening for clamping a conductor inserted through said side opening into electrical connection with the shell.

3. A fuse and connection block construction of the character described including a one piece base of molded insulation material, having a central mass provided with a depression opening to its tcp surface and containing a socket shell, a ledge in the nature of an end projection near the lower part of an end of the central mass, the inner part of the top surface of the ledge being below the adjacent part of the bottom surface of the central mass, these surface parts meeting to form an end opening communicating the space below the central mass with the space above the ledge, through which opening may pass a bus bar underlying the central mass and having an end overlying the ledge, the bus bar being assembled with the base by being passed through said opening and having its end accessible from the space above the block and the ledge, the central mass having a side opening communicating the space to one side of the block with the interior of the depression through which side opening a conductor terminal may be introduced into the interior of the depression, a shelf in the nature of an end projection near the lower part of a second end of the central mass, and

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having a conducting strap thereon provided' with binding screw means, and means in said socket shell having a head insulated from said shell and forming a center contact therefor, and having a shank threaded into the aforementioned bus bar.

4. A fuse and connection block construction of the character described including a one piece base of molded insulation material, having a central mass provided with a depression opening to its top surface and containing a socket shell, a ledge in the nature of an end projection near the lower part of an end of the central mass, the inner part of the top surface of the ledge being below the adjacent part of the bottom surface of the central mass, these surface parts meeting to form an end opening communicating the space below the central mass with the space above the ledge, through which opening may pass a bus bar underlying the central mass and having an end overlying the ledge, the bus bar being assembled with the base by being passed through said opening and having its end accessible from the space above the block and the ledge, the

central mass having a side opening communicating the space to one side of the block with the interior of the depression, through which side opening a conductor terminal may be introduced into the interior of the depression, a shelf in the nature of an end projection near the lower part of a second end of the central mass, and having a conducting strap thereon provided with binding screw means, and means in the socket shell in line with the side opening for clamping a conductor inserted through said side opening into electrical connection with the shell, and means in said socket shell having a head insulated from said shell and forming a center contact therefor, and having a shank threaded into the aforementioned bus bar.

' HARRISON J. L. FRANK. 

